Heat Recovery Steam Generators and many styles of Waste Heat Boilers have an internal liner and insulation system to protect the outer casing from hot exhaust gas. If the internal liner and insulation system fails, then many problems may occur including outer casing overheating and buckling, hot exhaust gas leaks, and insulation fouling of finned tubes and catalyst systems. In addition, the liner and insulation system may be exposed to more than 100 mile-per-hour exhaust gas velocities at a temperature of 1100° F. The exposure of the liner and insulation system to exhaust gas velocities at high temperature may cause vibration resulting in premature failure and increased maintenance/replacement expense.
The liner and insulation systems may be formed of: an outer pressure boundary which is commonly a ¼″ metallic plate; a layer or multiple layers of insulation; an inner liner of sheet metal which is selected to be compatible to the inside temperature of the Boiler, Heat Recovery Steam Generator, or Waste Heat Boiler. The inner liner may be constructed in a “fish scale” arrangement to allow for thermal expansion. The liner and insulation systems may also include a series of pins which are solidly attached to the outer pressure boundary to support the inner liner in a desired position/location. Washers may be placed over the pins in order to sandwich the inner liner between washers, allowing thermal expansion and restricting motion perpendicular to the outer pressure boundary.
In the past various ways have been used to sandwich the liner sheets of a liner or insulation system. In some embodiments, threaded fasteners are used. Alternatively, the upper washer may be welded directly to a pin. In all cases it is desirable that the sandwiching of the layers of the inner liner and insulation be snug, thereby eliminating vibration of the liner perpendicular to the outer pressure boundary.
Currently non-threaded pins are used in the fabrication of the insulated liner systems used with Boiler Systems including but not being limited to Heat Recovery Steam Generators or Waste Heat Boilers. During the use of non-threaded pins the compression of the internal liner and insulation toward the outer casing, and the sandwiching of the insulation between the liners, has occurred through the use of a vice-grip or other clamping device being releasably engaged to the tip of the pin. A hammer is then used to strike the clamping device in a downward direction until the sandwiched materials are snug relative to each other. A fabricator/worker/welder will then apply a sufficiently sturdy weld to the pin and top washer interface, to hold the assembly in a compressed configuration. The clamping device is then removed from the weld located proximate to the pin and top washer interface.
Alternatively, a flexible pry bar may be tack-welded to the tip of the top washer as disposed on the pin above the inner liner. The fabricator will then pry the top washer downwardly, thereby compressing the internal liner, insulation, and outer casing together, and the sandwiching of the insulation between the liners. The fabricator will then apply a sufficiently sturdy weld to the pin and top washer interface in order to hold the compressed liner assembly in a compressed configuration. The fabricator then removes the pry bar by breaking the tack weld and weld out between the pry bar and the pin and top washer interface.
During assembly of the liner and insulation system a fabricator will apply external force to the top washer to compress the internal liner, insulation, and outer casing together. If the liner and insulation system including a pin and washer is on an area designated as a floor surface, then the worker or fabricator may stand on the washer to compress the internal liner, insulation, and outer casing together immediately prior to welding. If the internal liner, insulation, and outer casing are disposed on an area designated as a side wall or overhead such as a ceiling, then force to compress the internal liner, insulation, and outer casing together must be applied by another method.
The art referred to and/or described above is not intended to constitute an admission that any patent, publication or other information referred to herein is “prior art” with respect to this invention. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 C.F.R. § 1.56(a) exists.
All U.S. patents and applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.
Without limiting the scope of the invention, a brief description of some of the claimed embodiments of the invention is set forth below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below.
A brief abstract of the technical disclosure in the specification is provided for the purposes of complying with 37 C.F.R. § 1.72.